Effects of water and fertilizer coupling on photosynthetic performance of flag leaves and plant nutrient utilization after anthesis of wheat

To investigate the effects of different water and fertilizer coupling on photosynthetic performance and plant nutrient utilization of post-anthesis flag leaf of wheat, a field experiment was conducted at the experimental base of Qingdao Agricultural University from October 2016 to June 2017. And two water levels (I1 and I2) and four fertilization levels (F1, F2, F3 and F4) were set. In terms of flag leaf light and performance of wheat, reasonable irrigation and fertilization (I1F1 and I1F4) of wheat can maintain a higher concentration of chlorophyll content, increase Gs, Pn and Tr, and reduce Ci. The Tr in I2F2 and I2F3 of wheat was very small, which was not conducive to CO₂ assimilation and to photosynthesis in wheat. In regard to nutrient utilization, the contents of N, P and K contents in roots, stems and leaves of wheat decreased gradually from elongation stage to filling stage. Reasonable coupled treatment (I1F1, I1F3, and I1F4) of water and fertilizer could increase the contents of N, P and K in root, stem and leaf of wheat. The results showed that I1F1 and I1F3 treatments played a favorable role in the photosynthetic performance of flag leaves and plant nutrient utilization, indicating that the treatment with 60 mm irrigation amount was more conducive to photosynthesis and plant nutrient utilization of wheat.